[#768] Remove generated css files from version control and add the sass compilation step to the Dashboard build process
[#768] Minify CSS files in production mode

* When used with RAKEP_MODE=production we want to "minify" the CSS file
  using YUI compressor
* We need to change the references to *.min.css
[#768] Make the regex on screen.min.css non-greedy
[#768] Made AssetfilePublic follow recent changes to Assetfile
[#768] Fix href path typo
[#768] Merge branch 'develop' into issue/768

Conflicts:
	Dashboard/app/css/main.css
Merge pull request #780 from akvo/issue/768

[#768] Remove generated css files from version control and add the sass ...